JPH1135734A - Production of recycled polyolefin resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a recycled resin compsn. which can be used esp. for producing films or sheets by melt mixing and kneading polyolefin resin films or sheets (crushing products) contg. org. substances other than polyolefin, mixing and kneading the mixture with water, and heating the resultant product at a specified temp. under a specified pressure to hydrolyze the org. substances other than polyolefins. SOLUTION: The polyolefin resin in an amount of 100 pts.wt. is mixed and kneaded with 0.1-50 pts.wt. water and then heated at 200-350 deg.C under a pressure of 10-30 MPa. It is advantageous to conduct the heating, melting, mixing, kneading, and hydrolysis with a mono-or multiscrew extruder. The hydrolysis can be conducted by mixing and kneading the resin with water by using an extruder to sufficiently disperse water in the resin, then elevating the pressure with a booster (e.g. a gear pump), and conducting the hydrolysis in a container. The hydrolysis time is pref. 0.5-30 min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a recycled polyolefin resin. More specifically, for example, the present invention relates to a method for producing a polyolefin resin composition which can be used as a film or sheet by recycling a waste polyolefin film or sheet containing a synthetic resin other than polyolefin in the form of a laminate layer or the like.

[0002]

2. Description of the Related Art Polyolefin resin films occupy a large part of the whole demand of polyolefin resins, but there are many problems in recycling waste materials, and most of them are incinerated or landfilled. In recent years, research on thermal decomposition has been advanced, and a method of decomposing into oil or gas and using it as a fuel or a raw material of the petrochemical industry again has been put to practical use. Although this recycling method is also an effective method for reusing resources, it is disadvantageous in that a large amount of energy is consumed and the processing cost is high before reuse.

[0003] In the case of reusing as a fuel, it is thought that it is more reasonable to compress a polyolefin resin into a solid fuel, and this method has been put to practical use. However, the most ideal method is to reuse a film or sheet as a film or sheet material again, and it is desired to realize this method. Polyolefin resin films, especially polyethylene films, are produced in the largest quantities and are used for many purposes including packaging. Films are required to have various properties depending on the application, and various modification treatments are performed to meet the requirements. As a modification method, various polymers are applied to the surface, laminated or laminated by coextrusion or the like to impart, for example, reinforcement or antifogging property, hydrophilicity, chargeability, adhesiveness, printability, and the like.

Therefore, many waste materials of polyolefin resin films and sheets contain many organic substances such as various synthetic resins in addition to polyolefin resins. When the polyolefin resin film or sheet as the waste material does not contain an organic substance such as a synthetic resin other than the polyolefin resin, its recovery and regeneration are easy. However, it is not easy to recycle a waste material of a polyolefin resin film or sheet on which an organic substance such as a synthetic resin other than the polyolefin resin is laminated to obtain a regenerated polyolefin resin composition that can be used particularly as a raw material of the film or sheet.

[0005] As a method of recycling polyolefin resin waste material, a waste material mainly composed of a thermoplastic resin such as a polyolefin resin and a thermosetting resin, for example, a vehicle bumper is melted.
A method is known in which water is added to hydrolyze and recover a thermosetting resin (see JP-A-7-124945).
However, even if this method is applied to recover and recycle a polyolefin resin film or a sheet waste material in which a polyolefin resin and a polyamide resin or a polyethylene terephthalate (PET) resin are laminated, the obtained regenerated resin composition is formed into a film. When this is done, there are bumps, and it is impossible to recycle the film.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to a polyolefin resin film or sheet containing a large amount of organic substances such as PET resin, polyamide resin and other synthetic resins in addition to the polyolefin resin, or a pulverized product thereof (hereinafter collectively referred to as these). It is an object of the present invention to provide a method for producing a reclaimed polyolefin resin composition which can be subjected to a regeneration treatment of a "polyolefin resin film or the like."

[0007]

SUMMARY OF THE INVENTION The present invention has been studied in order to achieve the above object, and as a result, it has been found that an organic substance mixed in a polyolefin resin film, a sheet and a pulverized product thereof is hydrolyzed under specific conditions. The inventors have found that the decomposition gives a regenerated polyolefin resin composition that can be used for the production of films and sheets, and completed the present invention. That is, the present invention heats, melts and kneads a polyolefin resin film, sheet or a crushed product thereof containing an organic substance other than the polyolefin resin, and then presents 0.1 to 50 parts by weight of water based on 100 parts by weight of the resin. Below, 200 ~
The gist of the present invention is a method for producing a recycled polyolefin resin composition, which comprises heating and pressurizing at 300 ° C. and 10 to 30 MPa to hydrolyze organic substances other than the polyolefin resin. The present invention will be described in detail.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Examples of the polyolefin resin film containing an organic substance other than the polyolefin resin to be regenerated in the present invention include, for example, low density polyethylene (LDPE) resin and linear low density polyethylene (LLDPE). ) Resin, high density polyethylene (HDP)
E) Resins, polypropylene resins, ethylene-vinyl acetate copolymers, and the like, or films made of composites of these resins, and the like.

In the present invention, the organic matter other than the polyolefin resin contained in the polyolefin resin film or the like to be recovered and regenerated is blended with the polyolefin resin constituting the polyolefin resin film or sheet, or bonded to the polyolefin resin film or sheet. Polyamide resin such as 6 nylon, 66 nylon, 12 nylon, PET, polybutylene terephthalate (P
Polyester resins such as BT); polycondensation resins such as polycarbonate resins; and fibers such as paper and grass and other wood chips. The most common polyolefin resin film containing an organic substance other than the polyolefin resin is a so-called laminate film in which various polycondensation-based resins form a laminated structure on a film or sheet made of various polyethylene or polypropylene resins. Is mentioned.

The various polyolefin resin films and the like to be regenerated by the method of the present invention include not only films and sheets, but also those obtained by kneading them in advance and forming pellets or powders. Any form may be used. In the present invention, various forms of polyolefin resin films and the like containing organic substances other than the polyolefin resin are first heated, melted and kneaded.

In this case, the quality may be adjusted by adding a new polyolefin resin in addition to the polyolefin resin film to be regenerated, etc., if necessary. Further, conventional additives to be added to the polyolefin resin, for example, an antioxidant, an ultraviolet absorber, an antistatic agent, other lubricants, dyes and pigments, etc. can be added and compounded. The heating temperature may be arbitrarily selected as a specific temperature from the range of 200 ° C. to 350 ° C.

The heating, melting, kneading and hydrolysis reaction treatments are advantageously carried out using a generally known single-screw or multi-screw extruder. In this case, the progress of the hydrolysis reaction depends on factors such as temperature, pressure and reaction time, and the reactivity of the target substance to be hydrolyzed, so that the operating conditions are wide. Therefore, the present invention is not limited to the range shown in the examples described later.

In the hydrolysis reaction treatment, thermal decomposition of the organic material other than the polyolefin resin is avoided at a temperature higher than the melting temperature of the polyolefin resin, and the organic material other than the polyolefin resin is reduced in a temperature range where the strength is not reduced. It is important to adjust the conditions so that the molecular weight is reduced to lower the melt viscosity and the kneading and dispersing in the polyolefin resin is facilitated. It is important to adjust the amount of water of the hydrolyzing agent to be used so that it is usually 0.1 parts by weight or more per 100 parts by weight of the resin mainly composed of polyolefin resin, so that the amount used is within the range where the extruder can be stably operated. Yes, the hydrolysis reaction is not accelerated when water is used in excess.

The lower limit of the preferred range of the hydrolysis reaction temperature is 200 ° C., preferably 250 ° C. or higher. On the other hand, the temperature is preferably 350 ° C. or less so that the strength does not decrease due to thermal decomposition of the polyolefin resin. Particularly preferably, it is within 320 ° C. The pressure of the hydrolysis reaction is 10 to 30 MPa. There is no upper limit for the pressure, but it is a mechanical limit when the pressure is increased by an extruder.

The necessary and sufficient reaction time varies depending on the object of the hydrolysis reaction, but is preferably 0.5 minutes or more. The time is not limited, but is preferably within 30 minutes as long as the polyolefin resin is not thermally deteriorated. Acid, alkali,
By adding salts, the hydrolysis reaction can be promoted. The hydrolysis reaction treatment is performed using a single-screw or multi-screw extruder.The outer resin and water are melted and kneaded with the extruder, the water is sufficiently dispersed in the resin, and the pressure is increased by a booster such as a gear pump. Thereafter, the hydrolysis reaction can be performed in a container. When the types of polyolefin resin constituting the polyolefin resin film and the like are mixed in various ways, it is difficult to adjust the melt viscosity of the resin to a constant value. As a result, the operating pressure of the extruder fluctuates and the hydrolysis reaction occurs. Becomes unstable. Therefore, when the operating pressure of the extruder is insufficient, a booster other than the extruder is used in combination as an auxiliary means for increasing the pressure by the extruder. Generally, a method of increasing the pressure using a pressure increasing device such as a gear pump is rational. The pressure of the hydrolysis reaction is 10 to 30 MPa. Although there is no upper limit for the pressure, it is a mechanical limit when the pressure is increased by a booster such as a gear pump.

The hydrolysis temperature and time are set at 200 to 350 ° C. and 0.5 as in the case where the hydrolysis reaction is carried out by an extruder.
-30 minutes are preferred. Water remains in the polyolefin resin composition that has undergone the hydrolysis reaction in the container, and the water is removed by evaporation. In order to finely disperse the decomposed product in the polyolefin resin, the polyolefin resin composition is transferred to another extruder and kneaded again. I do.
This method is effective for a regenerating treatment in the case where the polyolefin resin film is collected from a general market and the type of the polyolefin resin is variously mixed.

When a hydrolysis reaction is carried out by an extruder, for example, an LDPE resin composition having a melt flowability of resin (melt flow rate MFR at 190 ° C. for 10 minutes) of 2.8 is added to 30
After treatment at 0 ° C. and 10 MPa, L of MFR 0.9
When trying to hydrolyze the LDPE resin composition at 300 ° C., the pressure fluctuates to 16 MPa. Similarly, if an attempt is made to hydrolyze the MFR6 polypropylene resin composition at 300 ° C., the pressure drops to 5 MPa, and the treatment becomes impossible. In such a case, it is preferable to carry out hydrolysis by adjusting the pressure to a constant value using a booster such as a gear pump as described above.

In order to form a film or a sheet of the reclaimed polyolefin resin composition obtained in the present invention into a film or a sheet, if the hydrolysis reaction treatment is carried out using an extruder, it is necessary to carry out the hydrolysis step after this step. If necessary, the film may be passed through a filter and the film formation process can be started. When the hydrolysis treatment is performed using a container, this may be supplied to the extruder again, or may be brought to the film forming step, or may be pelletized once and supplied to the extruder again, Melt, knead, and if necessary, pass through a filter to form a film. In this case, it goes without saying that a new polyolefin resin may be blended into the recycled polyolefin resin composition. At the same time, the above-mentioned conventional additives which are usually blended with the polyolefin resin can be blended.

[0019]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. First, the equipment used in the examples will be described.

"Extruder" As an extruder, a twin screw extruder TEM35B, L / D = 32, manufactured by Toshiba Machine Co., Ltd. was used. "Gear pump" EX28 made by Swiss Marg
A / 28 type gear pump was used. "Hydrolysis reaction vessel" Fig.-3
45mmφ inside diameter, length 160mm, volume 250m shown in
1 pipe-shaped pressure-resistant container was used.

As a "screen changer" filter, an RSF45 type manufactured by Gnois Germany was used, and a screen having an aperture of 80 μm was mounted. The evaluation of the film was performed in the following manner. "Formation of Film for Evaluation" The resin pellet for evaluation was set at 180 ° C., blow ratio 2 and film thickness 5 using an inflation film molding machine φ50 mm extruder manufactured by Mitsubishi Heavy Industries, Ltd.
It was molded to 0 μm.

[Measurement of Dart Drop Strength] According to JIS Z1707, a weight having various loads was dropped on a film-shaped test piece, and the energy at which 50% of the test piece was broken was measured. "Measurement of number of spots" A fluorescent lamp is applied to the film-shaped test piece from below, and visually observed from above, and the spots (projections) of 0.1 mm or more in a range of 20 cm × 20 cm square are counted, and 1 gram of film is obtained. It was converted to per hit. "Measurement of flowability (abbreviated MFR)" JIS K7210-1
976 (for thermoplastics).

Example 1 A TEM35 extruder manufactured by Toshiba Machine Co., Ltd. was used to set the barrel setting temperature to 250 ° C.
1, a raw resin pellet obtained by mixing LLDPE film grade UF421 manufactured by Nippon Polychem Co., Ltd. and polyamide resin manufactured by Mitsubishi Engineering-Plastics Co., Ltd. and film grade 1022C6 at a weight ratio of 97 to 3 was supplied at a rate of 10 kg / h, Screw rotation speed 20
After kneading at 0 rpm and melting in the region 12 in FIG.
0.5 from the water supply port 13 with an Iwaki plunger pump
Water was supplied at a rate of kg / h, and the mixture was kneaded at a resin temperature of 300 ° C. and a resin pressure of 12 MPa in the hydrolysis reaction zone 14.

Water was discharged from the vent port 15 with steam, the resin was taken out from the strand nozzle 6, cooled in a water tank, and cut into pellets. The pellet was formed into a film, and the dirt drop strength was measured to be 1.2 J. As a result of visual observation of the appearance of the film, the number of bumps was 92 / g. The flowability MFR value of the resin is 1.1 g
/ 10 minutes.

Example 2 Pellets were obtained in the same manner as in Example 1 except that the resin temperature in the hydrolysis reaction zone 14 was 250 ° C. and the resin pressure was 15 MPa. The pellet was formed into a film, and the dirt drop strength was measured to be 1.2 J. As a result of visual observation of the appearance of the film, the number of bumps was 75 / g. The flowability MFR value of the resin is 1.0 g
/ 10 minutes.

Example 3 Pellets were obtained in the same manner as in Example 1 except that the amount of water supplied was 2 kg / h. The pellet was formed into a film, and the dart drop strength was measured.
J. As a result of visual observation of the appearance of the film, the number of bumps was 96 / g. The flowable MFR value of the resin was 1.1 g / 10 min.

Example 4 As an extruder, a TEM35 manufactured by Toshiba Machine Co., Ltd. was used, to which a gear pump 3, a hydrolysis reaction vessel 2, a screen changer 4, and a pressure regulating valve 5 were connected as shown in FIG. The machine barrel set temperature was set to 250 ° C., and from the resin supply port 11, LLDPE film grade UF421 manufactured by Nippon Polychem Co., Ltd. and polyamide resin manufactured by Mitsubishi Engineering-Plastics Corporation, film grade 1022
Raw material resin pellets obtained by mixing C6 at a weight ratio of 97: 3 are supplied at a rate of 10 kg / h, kneaded at a screw rotation speed of 200 rpm, and melted in a region of 12; 0.5kg with pump
/ H, and water was dispersed in the resin in the water dispersion region 14. The temperature and pressure of this dispersion region are 280 ° C. and 7
MPa. The temperature at the gear pump 3 is 280
C., the temperature of the hydrolysis zone is set to 300 ° C., the temperature at the screen changer 4 is set to 300 ° C., and the pressure of the mixture of resin and water is increased by the gear pump 3.
The pressure of the hydrolysis reaction region 21 is adjusted to 12 MPa with
Hydrolysis was performed at 300 ° C.

The resin was taken out in a state where it was foamed by the expansion of water vapor with the strand nozzle 6, cooled in a water tank, and pulverized to a particle size of 1 to 5 mm with a pulverizer. The resin is supplied to an extruder TEM3
After melt-kneading using the No. 5 (shown in FIG. 4), water vapor was discharged from the vent port, the resin was taken out from the strand nozzle 6, cooled in a water tank, and cut into pellets. The pellet was formed into a film, and the dirt drop strength was measured. As a result of visually observing the appearance of the film, the number of bumps was 76 / g. The flowable MFR value of the resin was 1.1 g / 10 min.

Example 5 The same apparatus and raw material resin pellets as in Example 4 were used, kneaded at a screw rotation speed of 200 rpm, melted in a region of 12 and then water was discharged from a water supply port 13 with a plunger pump manufactured by Iwaki Co., Ltd. At a rate of 0.5 kg / h, water was dispersed in the resin in the water dispersion area 14. The temperature and pressure in this dispersion region were 230 ° C. and 6 MPa, respectively. 2 gear pumps 3
30 ° C., the hydrolysis area was set at 250 ° C., the screen changer was set at 250 ° C., the mixture of the resin and water was pressurized with a gear pump, and the hydrolysis reaction area 21 was adjusted to 15 MPa with a 5 pressure control valve, and 250 ° C. For hydrolysis.

The resin is taken out in a state where it is foamed from the strand nozzle 6 together with water vapor, cooled in a water tank, and crushed by a pulverizer.
Milled to ５5 mm. Water vapor was discharged from the obtained resin in the same manner as in Example 4 to obtain pellets. As a result of measuring the dart drop strength by molding the pellets into a film,
It was 1.2J. As a result of visually observing the appearance of the film, the number of bumps was 63 / g. Resin flowability MF
The R value was 1.1 g / 10 minutes.

Comparative Example 1 Using a TEM35 extruder manufactured by Toshiba Machine Co., Ltd., the barrel setting temperature was set at 320 ° C.
Raw material resin pellets obtained by mixing LLDPE film grade UF421 manufactured by Nippon Polychem Co., Ltd. with polyamide resin and film grade 1022C6 manufactured by Mitsubishi Engineering-Plastics Co., Ltd. at a weight ratio of 97: 3 were supplied at a rate of 10 kg / h. Rotation speed 200
rpm, after melting in the regions of FIGS.
From 0.5, use an Iwaki plunger pump to supply 0.5 kg /
h, and the resin temperature of the hydrolysis reaction zone 14 is 360
And kneaded at a resin pressure of 10 MPa.

The water was discharged from the vent port 15 with steam, the resin was taken out from the strand nozzle 6, cooled in a water tank, and cut into pellets. The pellet was formed into a film, and the dirt drop strength was measured to be 0.6 J. As a result of visually observing the appearance of the film, the number of bumps was 497 / g. The flowability MFR value of the resin is 2.8.
g / 10 minutes. This result indicates that the LLDPE resin is decomposed and the dart drop strength is reduced and the flowability is increased, which is an unsuitable material for reuse as a resin.

Comparative Example 2 Pellets were obtained in the same manner as in Example 1 except that the resin pressure in the hydrolysis reaction zone 14 was changed to 5 MPa. The pellet was formed into a film, and the dirt drop strength was measured to be 0.8 J. As a result of visually observing the appearance of the film, the number of bumps was 1,230 / g. The flowable MFR value of the resin was 1.1 g / 10 min. The result is
It is presumed that the decomposition of the polyamide resin was insufficient, the dispersion in the LLDPE resin was poor, and a number of bumps occurred. The decrease in the dart drop strength is presumed to be the result of the decrease in the strength of the interface between the film and the bumps. As a result, it was found that the material was poor in appearance and strength, and was unsuitable for reuse as a resin.

Comparative Example 3 Pellets were obtained in the same manner as in Example 1 except that no water was supplied. The pellet was molded into a film, and the dirt drop strength was measured to be 0.3 J. As a result of visually observing the appearance of the film, the number of spots was 1,730 / g. The flowability MFR value of the resin is 1.
It was 1 g / 10 minutes. This result is presumed to be due to insufficient decomposition of the polyamide resin, poor dispersion in the LLDPE resin, and occurrence of a large number of bumps. The decrease in the dart drop strength is presumed to be the result of the decrease in the strength of the interface between the film and the bumps. As a result, it can be seen that the material is extremely poor in both appearance and strength, and is unsuitable for reuse as a resin.

Comparative Example 4 The temperature at the gear pump 3 was set at 320 ° C., the temperature at the hydrolysis area was set at 360 ° C., the temperature at the screen changer 4 was set at 300 ° C., and the mixture of resin and water was pressurized by the gear pump 3. A pellet from which water was removed was obtained in the same manner as in Example 4 except that the pressure in the hydrolysis reaction region No. 21 was adjusted to 10 MPa with the pressure control valve No. 5 and hydrolysis was performed at 360 ° C.

The obtained pellet is formed into a film,
As a result of measuring the dirt drop strength, it was 0.3 J. As a result of visual observation of the appearance of the film, the number of bumps was 1
It was 25 pieces / g. The flowability MFR value of the resin is 4.0 g.
/ 10 minutes. Although the number of spots is reduced by the hydrolysis reaction, the LLDPE resin is thermally degraded due to thermal decomposition, and the film strength is extremely reduced. This material is unsuitable for reuse as a resin.

Comparative Example 5 The pressure in the hydrolysis reaction zone of 21 was adjusted to 7 MPa,
Pellets from which water was removed were obtained in the same manner as in Example 4 except that hydrolysis was performed at 60 ° C. As a result of molding into a film and measuring the dart drop strength, 0.8 J
Met. As a result of visual observation of the appearance of the film, the number of spots was 810 / g. The flowable MFR value of the resin was 1.2 g / 10 min. The reduction of spots due to the hydrolysis reaction is insufficient, and this material is unsuitable for reuse as a resin.

[0038]

[Table 1]

[0039]

According to the method of the present invention, a series of operations including heating, melting, kneading and hydrolysis reaction treatment of a polyolefin resin film containing an organic substance other than the polyolefin resin are performed by one extruder, A low-cost recycled polyolefin composition can be obtained. In addition, when recovering and regenerating a polyolefin resin film or the like made of various polyolefin resins having different melt viscosities, stop the machine from regenerating the composition by combining a pressure booster such as an extruder and a gear pump and other reaction vessels. And a continuous hydrolysis reaction treatment can be performed. According to this method, it is possible to increase the pressure of the hydrolysis reaction to a higher pressure,
It is more advantageous for shortening the reaction time, preventing thermal deterioration, and improving the quality of the recycled polyolefin composition.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of an extruder used in carrying out the present invention.

FIG. 2 is a schematic explanatory view of an apparatus used in carrying out the present invention.

FIG. 3 is a schematic explanatory view of a hydrolysis reaction vessel used in carrying out the present invention.

FIG. 4 is a schematic explanatory view of an extruder used in carrying out the present invention.

[Explanation of symbols]

 Reference Signs List 1 twin screw extruder 11 resin supply port 12 resin melting area 13 water supply port 14 water dispersion area 15 vent port 16 hydrolysis reaction area 2 hydrolysis reaction vessel 21 hydrolysis reaction area 22 band heater 23 pressure / temperature sensor 3 gear pump 4 Screen changer 5 Pressure adjusting valve 6 Strand nozzle

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29K 105: 26

Claims (6)

[Claims] 1. A polyolefin resin film or sheet containing an organic substance other than a polyolefin resin or a crushed product thereof is melted and kneaded, and then 0.1 to 50 parts by weight of water is added to 100 parts by weight of the resin, followed by kneading. And then 200
A method for producing a reclaimed polyolefin resin composition, comprising heating and pressurizing to a temperature of from 350 to 350C and a pressure of from 10 to 30 MPa to hydrolyze organic substances other than the polyolefin resin. 2. The production method according to claim 1, wherein all of the steps from melting, kneading to hydrolysis are performed by using one extruder. 3. The method according to claim 1, wherein the melting, kneading, and kneading after adding water are performed in one extruder, and the hydrolysis is performed using a reaction vessel other than the extruder. 4. The production method according to claim 1, wherein the organic substance other than the polyolefin resin is a hydrolyzable synthetic resin. 5. The production method according to claim 1, wherein the hydrolyzable synthetic resin other than the polyolefin resin has a laminated structure with the polyolefin resin film. 6. A method for obtaining a film or sheet by forming a film of the recycled polyolefin resin composition obtained by the method according to claim 1.